Materials endowed with magnetic properties (e.g. ferromagnetic, ferrimagnetic or paramagnetic materials, shortly “magnetic materials”) can be used—as filling agents or fillers—in elastomer based compositions such as rubber based compositions to produce magnetic or magnetizable products, i.e. products having a permanent magnetic field or which are able to show magnetic characteristics in response to the application of an external magnetic field. Elastomer compositions including fillers (i.e. “magnetic fillers”) with magnetic properties are disclosed, for example, in EP-B-1 789 487.
Magnetic materials can be used for coverings to be applied to surfaces, for example to floors (or walls). On such coverings can then be applied, for example, magnetic carpets.
In order to achieve good magnetic properties, said elastomer compositions may require a high concentration of magnetic materials used as filling agents or fillers. Magnetic materials, however, are non-reinforcing materials, i.e. materials that do not have a reinforcement function. Thus, the compositions containing them may have the disadvantage of not having the appropriate mechanical properties for the desired application.
Moreover, the size of magnetic filler particles can also affect the mechanical properties of the resulting compositions.
Specifically, particles having a diameter size between and 200 nm (also known as nanoparticles or submicron particles) can be dispersed homogeneously in the composition without affecting the aesthetic appearance of the final product, for example following the crosslinking process. However, the incorporation of high amounts of such particles can cause an increase in the viscosity of the resulting composition and thus making difficult its processing phase.
On the contrary, the use of larger particles (for example with a diameter size comprised between 1 and 200 μm) can cause compatibilization problems between the magnetic filler and the elastomer, resulting in alteration of the physical-mechanical properties of the final product.
Magnetic elastomer compositions can therefore be difficult to employ, for example, for making coverings of surfaces, such as floorings or wall coverings. With respect to floorings, for example, in order to be suitable for such specific use, they must comply with specific technical standards that may regulate, for example, abrasion resistance (measured, for example, according to ISO 4649 method), indentation resistance (measured, for example, according to EN ISO 24343 method), tear resistance (measured, for example, according to the ISO 34-1 method) or corrosion resistance by chemicals (measured, for example, according to EN ISO 26987 method).